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However, Elizondo became nervous and dumped them on the nearby highway instead.

He is being held without charge at a special detention facility while prosecutors build their case against him.

An official said Elizondo had confessed to killing members of the Gulf cartel and burning or burying their bodies in another area of Nuevo Leon.

Victims: Officials carry one of the 49 mutilated bodies found on the highway

The massacre is one of the worst atrocities committed in Mexico's drug war, which has raged since President Felipe Calderon took power in 2006 and launched a national offensive against the cartels.

Police found the corpses on the highway about 18 miles east of the city of Monterrey, Mexico on May 13.

As the bodies lacked heads, hands and feet, police said they could only identify them using DNA, yet a week later none of the victims have been identified, investigators said.

Police said they have found no signs of recent mass disappearances in the region and the victims could be migrants from Central or South America passing through Mexico on the way to the United States.

Drug cartels often kidnap foreign migrants for ransom, killing those who do not pay.

Security: Forensic experts had to be guarded by police and army members as they investigated the crime scene last week

Graffiti sprayed at the scene of the corpses showed the mark of the Zetas, who are fighting for control of the region.

A video that allegedly shows the men dumping the bodies was also posted on the internet.

The 'Z' symbol of the Zetas cartel painted on a pillar near a crime scene

In the film, men can be seen pulling a large pile of corpses from a truck onto the road during the night.

They are then seen leaving a message on a blanket threatening security forces and the rival Gulf and Sinaloa cartels.

Signed by the Zeta leaders the message was clear: 'Gulf cartel, Sinaloa cartel, marines and soldiers, nobody can do anything against us or they will lose.'

However, over the following days messages were put up in several Mexican states claiming the Zetas were not behind the massacre - an unusual measure as the gang openly admits its involvement in many mass killings.

The Zetas were founded by former soldiers who defected from the Mexican military in 1998 to work as hired killers for drug traffickers.

They have since carved out their own smuggling empire, expanded massively across Mexico and diversified into kidnapping, extortion and theft of crude oil.

In recent weeks, violence between the Zetas and their rivals has intensified in several parts of Mexico.

Among the worst incidents saw 18 people were decapitated near the city of Guadalajara and nine victims hanged from a bridge in the city of Nuevo Laredo, across the border from Laredo, Texas.

In total, around 55,000 people have died in drug related violence and more than 5,000 have disappeared in Mexico since Calderon took office in December 2006.

The victims included six women, and police have confirmed that some of the bodies were found in bags and others uncovered